This invention relates, in broad terms, to the field of vehicular (principally automotive) crash systems and relates, in particular, to vehicular bumper assemblies that are provided with a forwardly-disposed towing facility whereby a vehicle may be towed by another.
A number of important considerations must be borne in mind during the design and production of such bumper assemblies. First and foremost, the impact-absorbing function of the bumper must be carefully monitored, so as to ensure that as much impact energy as possible is absorbed by the bumper assembly, and thus not transmitted to the main vehicle structure, or to the occupants thereof.
To this end, bumper assemblies typically comprise a metallic (sometimes rolled) front beam which may be attached, towards a rear part thereof, to a crash box, which is typically designed to deform (“crumple”) under an impact condition. Alternatives to crash box systems are also known, in which the front beam is attached directly to a vehicle chassis rail, with the rail sometimes being provided with a sacrificial element to perform the energy-absorbing function. In both cases, however, the front face of the metallic beam is usually provided, for cosmetic reasons, with a covering, or skin, although such components contribute little to the impact-absorbing characteristics of the overall bumper assembly.
It has also become common practice, particularly in the domestic and light commercial vehicle industries, to provide, in conjunction with a front bumper assembly, some means whereby the vehicle concerned can be towed by another vehicle, in the case of breakdown, accident damage, insufficient fuel and the like.
To provide this capability, a so-called “tow nut” is attached to or provided with the forwardly-disposed bumper beam, with the tow nut having an internal thread to receive an externally threaded “tow eye” or “tow hook” having a circular or hooked end, by which a rope or other such line may be used to connect the towed and towing vehicles together. The term “tow nut” should thus be interpreted broadly, by reference to the function that it performs: it need not, of course, be “nut” shaped.
However, problems have arisen with currently available towing assemblies, principally as the rigid nature of the tow nut and its securement to the forwardly-disposed bumper beam seriously hinders the ability of the beam to crumple under impact conditions. In addition, as it has become the norm to provide a single tow nut towards one end of the forward bumper beam (and thus to one side of the front of the vehicle), the strength and hence impact-absorbing characteristics of the beam vary considerably along its length. As will be understood, this means that a vehicle provided with such a bumper assembly will suffer different types and amounts of damage during a collision, depending on which part of the vehicle is struck.
It is an object of the present invention to provide an improved tow nut that overcomes or at least reduces these problems. Other objects of the invention are to provide improved towing and vehicle bumper assemblies.